package com.sosky;

import java.util.LinkedList;
import java.util.List;

/**
 * 946. 验证栈序列
 * <p>
 * 给定 pushed 和 popped 两个序列，每个序列中的 值都不重复，
 * 只有当它们可能是在最初空栈上进行的推入 push 和弹出 pop 操作序列的结果时，返回 true；否则，返回 false 。
 * <p>
 * 示例 1：
 * 输入：pushed = [1,2,3,4,5], popped = [4,5,3,2,1]
 * 输出：true
 * 解释：我们可以按以下顺序执行：
 * push(1), push(2), push(3), push(4), pop() -> 4,
 * push(5), pop() -> 5, pop() -> 3, pop() -> 2, pop() -> 1
 * <p>
 * 示例 2：
 * 输入：pushed = [1,2,3,4,5], popped = [4,3,5,1,2]
 * 输出：false
 * 解释：1 不能在 2 之前弹出。
 * <p>
 * 提示：
 * 0 <= pushed.length == popped.length <= 1000
 * 0 <= pushed[i], popped[i] < 1000
 * pushed 是 popped 的排列。
 */
public class Solution946 {
    public static void main(String[] args) {
        System.out.println(validateStackSequences(new int[]{1, 2, 3, 4, 5}, new int[]{4, 5, 3, 2, 1}));
        System.out.println(validateStackSequences(new int[]{1, 2, 3, 4, 5}, new int[]{4, 3, 5, 1, 2}));
    }

    public static boolean validateStackSequences(int[] pushed, int[] popped) {
        boolean flag = false;
        if (pushed.length == 0 || popped.length == 0) {
            return true;
        }
        int idx = 0;
        List<Integer> stack = new LinkedList<>();
        for (int i = 0; i < pushed.length; i++) {
            System.out.println("push: " + pushed[i]);
            stack.add(pushed[i]);
            while (stack.size() > 0 && stack.get(stack.size() - 1) == popped[idx]) {
                System.out.println("pop: " + stack.get(stack.size() - 1));
                stack.remove(stack.size() - 1);
                idx++;
            }
        }
        if (idx == popped.length) {
            flag = true;
        }
        return flag;
    }
}
